Radiotube



April 1, 1930. H. c. COLBURN 1,752,520

HADIOTUBE Filed Aug. 18, 1924 2 Sheets-Sheet l 111 24 l 19,? g 6 14 a" 5 INVENTOR. flsmssnr C. Coral/m April 1, 1930. H. c. COLBURN RADIOTUBE 2 Sheets-Sheet 2 Filed Aug. 18, 1924 7 [NYE/(T0)? HERBERT 0. Cozsun Patented Apr. 1, 1930 PATENT OFFICE HERBERT C. COLBURN, OF SAN LEANDBO, CALIFORNIA RADIOTUBE Application filed August 18, 1924. Serial No. 782,683.

My invention is an improved radio tube, adaptable to the detecting or amplification of radio impulses.

An ob ect of the invention is to provide a unit of this character in which two or more thermionic units are positioned within a single bulb, with the leads for electrodes of each unit so arranged as to greatly reduce caacity therebetween. This I accomplish by ringing the leads to the plate and grid of each of the respective units out of opposite ends of the bulb.

Other objects and advantages will be more specifically described and pointed out in the following detailed description.

In the annexed drawing I have shown the preferred form of my invention, but it may also be embodied in other forms, and in this application I desire to cover my invention in 2 w atever form it may be embodied.

Figure 1 is a side view of my tube.

Figure 2 is a sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a diagrammatic view of my tube.

Figure 4 is a wiring diagram illustrating an application of the present invention.

Referring more particularly to the drawing, the bulb 1 is preferably formed with two constricted ends 2 and 3, in which the usual mounting presses 4 and 5 respectively are positioned.

A pair of cylindrical plate members 6 and 7 are positioned in the bulb 1, and are supported on rods 8 and 9 respectively secured thereto, and embedded in the presses 4 and 5 respectively. Conducting wires 10 and 11 are secured to the rods 8 and 9 respectively and are secured to suitable external terminals 12 and 13 respectively.

Coiled grid members 14 and 15 are ositioned within the plate members 6 and res ectively, and are supported on rods 16 and 1? respectively, which are embedded in the presses 5 and 4 respectively.

Wires 18 and 19 extend from the rods 16 and 17 respectively and are secured to suitable terminals 20 and 21 respectively.

Incandescent filament wires 22 and 23 extend through the grid members 14 and 15 respectively and are supported on rods 24 and 25 embedded in the presses 4 and 5 respectively. Wires 26 and 27 extend from the rods 24 and 25 respectively to terminals 28 and 29 respectively.

From this it will be seen that I have provided within a single tube 1, two thermionic translating units, one of which comprises plate 6, grid 14 and filament 22 and the other of which comprises plate 7, grid 15 and filament 23. It will also be observed that the grid terminal and plate terminal of one of the units are at opposite ends of the tube, for example the lead 10 from the plate 6 is brought out of the tube through the end 2 thereof whereas the lead 18 from the grid 14 is through the opposite end of the tube 1. The other unit is similarly arranged. In this manner the leads from the electrodes of each unit within the tube are brought out 7 therefrom at the greatest distance apart possible, thereby reducing capacity between the leads to a minimum.

It is to be understood that I do not limit my invention to any particular use, since, both units may be used as radio frequency or audio frequency amplifiers, or one unit may be used as a detector and the other as an amplifier. For the purpose of illustrating an application of my invention, I have shown in Fig. 4 a receiving circuit of the reflex type,

in which my improved tube is shown diagrammatically with corresponding parts given reference numerals similar to those above set forth. In said Fig. 4, an antennae 30 is connected with one end of a primary coil 31, the opposite end of which is grounded through a lead 32. A variable condenser 33 is shunted across the secondary coil 34, one end of which is connected with grid 14, and the other end of which is connected with the filaments 22 and 23 which are connected with the negative side of an A battery through lead 35 and with the positive side thereof a through lead 36, the negative pole of the A battery being grounded through lead 37. The plate 6, adjacent the grid 14, is connected with the primary coil 38 of a radiofrequency transformer. The other terminal of said coil is connected through a lead 39 to the positive pole of the B battery. The negative pole o the B battery is connected with the positive pole of the A battery. The secondary coil 40 of the radio frequency transformer is connected through the crystal detector 41 to one terminal of the primary coil 42 of the audio frequency transformer. The

lower terminals of coils 40 and 42 are con-v nected by a wire 43. The secondary coil 44: of the audio frequency transformer is connected with the negative pole of the A battery through a lead 45 and to the second grid 15 through a lead 46. The plate 7 adjacent the grid 15 is connected to one terminal of the telephones 47, the other terminal of which is connected to lead 39, thus completing the circuits.

Having described my invention, I claim:

1. A radio tube having two thermionic translating units each comprising a plate, a grid and a filament, presses within said tube at opposite ends thereof for supporting the elements of said units, the grid of each unit being supported on a press different i from that on which the plate of the same unit is supported.

2. A radio tube having two thermionic translating units each comprising a plate, a grid and a filament, presses Within said tube at opposite ends thereof for supporting the elements of said units, each of the presses supporting the plate of one of said units and the grid of the other of said units whereby the capacity between the leads to the elements of the tube is reduced to a minimum.

In Witness whereof I afiix my signature.

HERBERT G. COLBURN. 

